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From |
"Roger B. Newson" <r.newson@imperial.ac.uk> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: Not sure how to interpret -somersd- results |

Date |
Wed, 02 Oct 2013 21:57:51 +0100 |

Hello Monica

transf(z) tdist

I hope this helps. Let me know if you have any more queries. Best wishes Roger Roger B Newson BSc MSc DPhil Lecturer in Medical Statistics Respiratory Epidemiology and Public Health Group National Heart and Lung Institute Imperial College London Royal Brompton Campus Room 33, Emmanuel Kaye Building 1B Manresa Road London SW3 6LR UNITED KINGDOM Tel: +44 (0)20 7352 8121 ext 3381 Fax: +44 (0)20 7351 8322 Email: r.newson@imperial.ac.uk Web page: http://www.imperial.ac.uk/nhli/r.newson/ Departmental Web page: http://www1.imperial.ac.uk/medicine/about/divisions/nhli/respiration/popgenetics/reph/ Opinions expressed are those of the author, not of the institution. On 02/10/2013 21:47, Jain, Monica (HarvestPlus) wrote:

I am using -somersd- and I am unsure how to interpret the results to test stochastic dominance. I am using Stata 13 for Windows. I have a two year cross-section data on heights of children 3-5 years. I want to check if the distribution of heights z-score of children in 2006 first order stochastically dominates those in 1996. From previous threads on stochastic dominance, I saw that one could use Somers D statistic for it. I am using the following command where 2006 is year=1, haz is the height z-score: somersd year haz, cluster(district) and I get the following result: Somers' D with variable: year Transformation: Untransformed Valid observations: 627 Number of clusters: 4 Symmetric 95% CI (Std. Err. adjusted for 4 clusters in dist) ------------------------------------------------------------------------------ | Jackknife year | Coef. Std. Err. z P>|z| [95% Conf. Interval] -------------+---------------------------------------------------------------- haz06 | .357832 .0434275 8.24 0.000 .2727157 .4429483 -------------+---------------------------------------------------------------- What I know is that the above result indicates that a randomly selected child in 2006 is 36% more likely to have a higher height z-score than a randomly selected child in 1996, than vice versa. But, what I do not know is how do I state this result in terms of stochastic dominance. Can I say that distribution of height z-scores in 2006 first order stochastically dominates the distribution of height z-scores in 1996? Alternatively, can I make any statement about stochastic dominance from the above result? If yes, what would it be? Monica Jain * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/faqs/resources/statalist-faq/ * http://www.ats.ucla.edu/stat/stata/

* * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/faqs/resources/statalist-faq/ * http://www.ats.ucla.edu/stat/stata/

**References**:**st: Not sure how to interpret -somersd- results***From:*"Jain, Monica (HarvestPlus)" <M.Jain@cgiar.org>

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